This application is based upon, claims the benefit of priority of, and incorporates by reference the contents of prior Japanese Patent Application No. 2001-359586 filed Nov. 26, 2001.
1. Technical Field of the Invention
The present invention relates to a cold thermal energy storage type vehicle air conditioner having a cold thermal energy storage unit cooled by cold air passed through a cooling evaporator, and the invention is applied to a vehicle whose vehicle engine, a driving source for a compressor is stopped when the vehicle stops moving.
2. Description of Related Art
Generally, for the purpose of environmental protection, a vehicle that automatically stops its engine when the vehicle stops moving, for example, to wait for a green light, has been commercially available. This vehicle is known as an eco-run or ecology running vehicle and an example of such a vehicle is a hybrid car. In the future, more vehicles are likely to exhibit the same engine stopping function when the vehicle stops.
In a vehicle""s air conditioner, the compressor in the refrigeration cycle is driven by the vehicle engine, and therefore every time the above eco-run car stops moving, which stops the engine, the compressor also stops and the temperature in the cooling evaporator increases. This raises the temperature of air blown into the vehicle cabin, and reduces the comfort of the passengers as they cannot continue to feel cool enough because the increase in air temperature.
Therefore, there is an increasing demand for a cold thermal energy storage type vehicle air conditioner that includes a cold thermal energy storage unit. The cold thermal energy storage unit will store cold thermal energy during the operation of the compressor, and can cool air blown into the cabin by the cold thermal energy storage unit when the compressor is stopped (when the cooling function by the cooling evaporator stops).
This invention presents a cold thermal energy storage type vehicle air conditioner. If the cold thermal energy quantity stored in the cold thermal energy storage unit is small while the vehicle runs, there is only a short supply time for cooling air to be blown into the vehicle cabin at a comfortably low temperature when the engine is stopped. Therefore, the stored cold thermal energy quantity while the vehicle runs, that is, while the engine operates, must be known.
The invention is directed to a solution to the above problem. It is an object of the invention to provide a cold thermal energy storage type vehicle air conditioner that allows the quantity of cold thermal energy stored in the cold thermal energy storage unit during the operation of the vehicle engine to be accurately calculated. Another object of the invention is to provide a cold thermal energy storage type vehicle air conditioner that allows air conditioning control to be accurately carried out when the vehicle engine is stopped depending upon the stored quantity of cold thermal energy stored in the cold thermal energy storage unit.
In order to achieve the above object, according to a first aspect of the invention, in a vehicle air conditioner there is a cold thermal energy storage unit (40) provided on the downstream side of an evaporator (9) and cooled by cold air passed through the evaporator (9). The air blown into the cabin is cooled by a quantity of the stored cold thermal energy of the cold thermal energy storage unit (40) when the vehicle engine (4) is stopped. The cold thermal energy storage unit (40) has a cold thermal energy storage material (44) cooled and solidified by the cold air passed through the evaporator (9).
During the operation of the vehicle engine (4), the cold thermal energy storage time is measured. This is accomplished by measuring the time for the temperature of the cold thermal energy storage unit (40) to reach the solidifying point of the cold thermal energy storage material (44) or lower. The stored cold thermal energy quantity of the cold thermal energy storage material (44) during the operation of the vehicle engine (4) is calculated based on information including at least the cold thermal energy storage time and the volume of the cold air.
Meanwhile, cold thermal energy by latent heat is stored in response to the temperature of the cold thermal energy storage unit (40) reaching the solidifying temperature, or lower, of the cold thermal energy storage material (44). Therefore, the time after the temperature of the cold thermal energy storage unit (40) reaches the solidifying temperature, or lower, of the cold thermal energy storage material (44) and the volume of the cold air, are pieces of information most related to the cold thermal energy storage heat quantity of the cold thermal energy storage material (44). Therefore, the stored cold thermal energy quantity of the cold thermal energy storage material (44) is calculated based on information including at least the time after the temperature of the cold thermal energy storage unit (40) reaches the solidifying point, or lower, of the cold thermal energy storage material (44), i.e., the cold thermal energy storage time and the volume of cold air. Therefore, stored cold thermal energy quantity of the cold thermal energy storage material during the operation of the vehicle engine (4) can accurately be calculated.
Additionally, there is a temperature detecting means (32) for detecting the temperature of the evaporator (9) and a temperature detecting means (33) for detecting the temperature of the cold thermal energy storage unit (40). The stored cold thermal energy quantity is calculated based on the cold thermal energy storage time, the volume of the cold air, the temperature of the evaporator (9), and the temperature of the cold thermal energy storage unit (40).
Meanwhile, the stored cold thermal energy quantity of the cold thermal energy storage material (44) corresponds to the temperature of air of the cold thermal energy storage unit (40) before and after cold thermal energy storage. In other words, the quantity corresponds to the temperature difference before and after cold thermal energy storage. Therefore, the temperature difference between them (9, 10) based on the temperatures of the evaporator (9) and the cold thermal energy storage unit (40) is taken into consideration in calculating the stored cold thermal energy quantity of the cold thermal energy storage material, and therefore the stored cold thermal energy quantity can more accurately be calculated.
According to another aspect of the invention, in a vehicle air conditioner in which there is a cold thermal energy storage unit (40) provided on the air downstream side of an evaporator (9) and cooled by cold air passed through the evaporator (9), and air blown into the cabin is cooled by the stored cold thermal energy quantity of the cold thermal energy storage unit (40) when the vehicle engine (4) is stopped, the cold thermal energy storage unit (40) has a cold thermal energy storage material (44) cooled and solidified by the cold air passed through the evaporator (9). During operation of the vehicle engine (4), the cold thermal energy storage completion time, after the temperature of the cold thermal energy storage unit (40) reaches the solidifying point, or lower, of the cold thermal energy storage material (44), that is, until cold thermal energy storage to the cold thermal energy storage material (44) is completed, is pre-set for each air volume of cold air.
During operation of the vehicle engine (4), the time passed, after the temperature of the cold thermal energy storage unit (40) reaches the solidifying point, or lower, of the cold thermal energy storage material (44), is measured. The pre-set cold thermal energy storage completion time is selected based on the actual cold air volume after the temperature of the cold thermal energy storage unit (40) reaches the solidifying point, or lower, of the cold thermal energy storage material (44). The stored cold thermal energy quantity of the cold thermal energy storage material (44) during operation of the vehicle engine (4) is calculated based on the ratio of the passed time relative to the selected cold thermal energy storage completion time.
In this way, using the ratio between the time passed after the temperature of the cold thermal energy storage unit reaches the solidifying point, or lower, of the cold thermal energy storage material and the pre-set cold thermal energy storage completion time selected based on the air volume at the time, the stored cold thermal energy quantity of the cold thermal energy storage material (44) can accurately be calculated.
According to another aspect of the invention, in a vehicle air conditioner in which there is a cold thermal energy storage unit (40) provided on the downstream side of an evaporator (9) and cooled by cold air passed through the evaporator (9), air blown into the cabin is cooled by the stored cold thermal energy quantity of the cold thermal energy storage unit (40) when the vehicle engine (4) is stopped. The cold thermal energy storage unit (40) has a cold thermal energy storage material (44) cooled and solidified by the cold air passed through the evaporator (9).
A stored cold thermal energy quantity calculating means (S50) calculates the stored cold thermal energy quantity of the cold thermal energy storage material (44) during the operation of the vehicle engine (4). When the vehicle engine (4) is stopped, the volume of air blown into the cabin that can be cooled by cold thermal energy radiation of the cold thermal energy storage material (44) for a prescribed duration is calculated based on information including at least the stored cold thermal energy quantity and the duration, and the volume of air blown into the cabin, and is controlled to be the calculated air volume.
In this way, the volume of air blown into the cabin that can be cooled by cold thermal energy radiation of the cold thermal energy storage material (44) for a prescribed duration is calculated, and the volume of air blown into the cabin when the vehicle engine (4) is stopped is controlled to be the calculated air volume. Therefore, regardless of an increase or decrease in the stored cold thermal energy quantity when the vehicle engine (4) is stopped, the air volume corresponding to the actual stored cold thermal energy quantity is selected for cooling when the engine is stopped, so that cooling by cold thermal energy radiation of the cold thermal energy storage material (44) can be continued during the prescribed duration.
According to a fifth aspect of the invention said calculated air volume is calculated based on information including at least the stored cold thermal energy quantity, the duration, and the temperature of.the air taken into the cold thermal energy storage unit (40). Since the stored cold thermal energy quantity of the cold thermal energy storage material (44) is affected by the temperature of the air taken into the cold thermal energy storage unit (40), the temperature of the intake air is taken into consideration in calculating said air volume, so that said air volume can more accurately be calculated.
According to a sixth aspect of the invention, when the vehicle engine (4) is stopped, an air volume manually set using an air conditioning control panel (36) or an air volume automatically set by automatic control is calculated as a first volume of air blown into the cabin, said calculated air volume is a second air volume, and the smaller air volume between the first and second air volumes is selected as the volume of air blown into the cabin when the vehicle engine (4) is stopped.
In this way, when the engine is stopped, and the first air volume is smaller than the second air volume, the air volume of air blown into the cabin is automatically set as the first air volume, the air volume by the operation of the passengers by their will or the air volume automatically set by auto control can be selected, so that the comfort of the passengers in relation with air conditioning when the engine is stopped can be improved.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.